Switching statins leads to lower persistence with therapy

Patients who switch statins have lower persistence to therapy compared to those who don’t switch, found Gary J. Tereso, PharmD, director of pharmacy services at Health New England, Springfield, Mass. The poster “Evaluation of adherence and persistence in members who switched statins” was presented at the 45th midyear meeting of the American Society of Health-Systems Pharmacists.

A retrospective review of patients who were prescribed a statin was conducted. Patients were followed for 360 days from the date of their index claim.

The patients were divided into 2 groups: the 1,331 who were newly prescribed a statin (no statin prescription during the 180 days before the index date) and the 7,556 who were previously prescribed a statin during the 180 days prior to the index date.

A switch was defined as any prescription for a non-index statin during follow-up, with the exception of a generic equivalent switched for the index statin.

Some 129 of the 1,331 who were new users of statins switched; the most common switch was from simvastatin to atorvastatin (42 patients; 33.6%).

Of the 7,556 who were previously prescribed a statin, 767 switched products; 24.5% who were on atorvastatin switched to simvastatin, 8.7% who were prescribed lovastatin switched to simvastatin, 13.8% who were on simvastatin switched to atorvastatin, and 7.2% who were on simvastatin/ezetimibe switched to simvastatin.

Among the switchers, 38.2% of the newly prescribed group and 44.5% of the previous statin users had a proportion of days covered (the number of days the medication was available divided by the total number of days of the follow-up period) of at least 80%, compared to 41.6% and 56.2%, respectively, of those who didn’t switch.

“Persistence at 1 year was significantly higher in members who did not switch therapy, and more members not switching had a high proportion of days covered compared to members who switched statin,” according to Dr. Tereso.

Persistence at 360 days was 16.3% (new users) and 26.3% (previous users) compared to 25.0% (new users) and 38.5% (previous users) in the nonswitchers.

“The results demonstrate the potential unintended consequences of switching therapy on medication adherence and persistence, and warrant further review,” said Dr. Tereso.